Etiology, or etiology, consists in the study and research of the causes of a specific phenomenon. In the medical field, in particular, etiology investigates the factors that can intervene in the origin of diseases, studying their importance and possible relationships of interdependence. In many cases, in fact, diseases do not have a single cause, but rather a "multiple" or "multifactorial" etiology; in practice, this means that several causal agents (or etiological agents concur simultaneously) at their origin and evolution. ).
Typical pathologies with multifactorial aetiology are the so-called "wellness diseases", such as type II diabetes mellitus, arterial hypertension, atherosclerosis and their related complications (ischemic heart disease, intermittent claudication, peripheral neuropathy, etc.). More rarely, the etiology is single and well defined; this is the case, for example, of genetic anomalies, intoxications or infectious diseases, which can in any case find more or less fertile ground in relation to the general state of health of the organism (defenses immunity, nutritional status, stress, etc.) and external factors (climate, overcrowding, poor or excessive hygiene, etc.).
